Myrtle rust alert

Growers may be wondering about the risks posed by myrtle rust to durable eucalypts. Because this is the first time myrtle rust has been found in New Zealand, the best experience comes from across the Tasman, where the disease has been evident for some time. At our recent workshop, Dr Tim Wardlaw (Forestry Tasmania) gave a presentation on 'Managing the Health of Plantation Eucalypts' which includes information on the susceptibility of different eucalypts to myrtle rust. The video and powerpoint of Dr Wardlaw's talk are available.

Dr Tara Murray, School of Forestry, University of Canterbury, says:"Young soft foliage is particularly susceptible to myrtle rust and known eucalypt hosts grown in New Zealand include E saligna, E. botryoides, E. pilularis, E. regnans and E. nitens (Colley, 2005). Modelling based on suitable environmental conditions for rust survival indicate much of the North Island (except the central plateau) and parts of Marlborough and North Canterbury can be expected to fall within the future geographical range of myrtle rust (Kriticos and Leriche 2008). This includes areas where durable eucalypts have already been established as part of the NZDFI programme.

It is unlikely myrtle rust can be eradicated so depending on the extent of it’s impact there could be the obvious need to identify the least susceptible eucalypt genotypes within the current breeding populations. We also recognize the potential implications for all other aspects of the durable eucalypt research programme which involve the movement of plant material. Therefore protocols are to be developed and implemented with regard to the movement of plant material and personnel between field sites and between the field and research institutions to ensure we do not aid the spread of either pest or pathogen. This is planned over the next 6 months."

MPI Myrtle rust alertMyrtle rust (Austropuccinia psidii) is a serious fungal disease that affects plants in the myrtle family. Plants in this family include a nuber of NZ native species including the iconic pōhutukawa and mānuka as well as eucalypts. It has been found in Northland, Waikato, Bay of Plenty and Taranaki. It is also widespread on Raoul Island in the Kermadec group, about 1,100km to the north-east of New Zealand.

Myrtle rust spores are microscopic and can easily spread across large distances by wind, or via insects, birds, people, or machinery. It is thought the fungus arrived in New Zealand carried by strong winds from Australia. There have been a number of significant weather events capable of transporting spores here and the discovery of the disease in large, established trees lends weight to this assumption.

MPI and the Department of Conservation (DOC), with the help of local iwi, the nursery industry and local authorities are running a large operation to determine the scale of the situation and contain and control myrtle rust in the areas it has been found.

If you think you’ve seen any signs of myrtle rust, don’t touch it, take a photo and call 0800 80 99 66.

NZFFA Briefing Document

As long ago as 2010, the NZFFA recognised that myrtle rust could pose a threat to farm forestry crops. A briefing paper was produced by Scion which includes information on the life cycle of the disease and information about the regions where it is most likely to thrive.